All Signs Point to Hidden Ocean on Saturn Moon Titan

A huge ocean of liquid water may indeed slosh about beneath the frigid surface of Saturn's moon Titan, according to new evidence collected by a NASA spacecraft. 

The observations were made by NASA's Cassini probe, which has been eyeing Saturn and its rings and moons from orbit since arriving at the gas giant in 2004.
Certain details of Titan's orbit and rotation aren't compatible with the behavior of a celestial body that is completely solid all the way through. But these details make a lot of sense if the huge moon is assumed to have a subsurface ocean, likely of liquid water, researchers said.

Titan, the largest of Saturn's more than 60 known moons, is considered one of the leading candidates to host life beyond Earth. Space.com